1. Field of the Invention
The invention relates to an inkjet printhead and its manufacturing method, and in particular, the invention relates to an inkjet printhead with high driving force.
2. Description of the Related Art
In a conventional inkjet printhead 10, an open-typed ink chamber is provided as shown in FIG. 1. Numeral 11 represents a feed channel, numeral 12 represents a heating device, numeral 13 represents an island for filtering the ink, and numeral 14 represents a cross section of an ink slot. The ink flows to the front side of the chip from the rear via the ink slot 14, and then fills the ink chamber via the feed channel 11. After a pulse voltage is applied to the heating device 12, the temperature of the heating device increases to generate bubbles. The ink is then dispensed via a nozzle plate, and re-supplied via the feed channel 11.
During the manufacture of the chip of the conventional inkjet printhead, the ink slot is necessary so that the ink can flow to the feed channel from an ink cartridge. The ink slot is formed by drilling through the chip. During drilling, the chip is continuously etched by fine, hard SiC powder for a long time, making it easily damaged. Also, the reliability of such drilling process is low, reducing the yield of the chip. Additionally, for a color inkjet printer with high resolution, three ink slots are formed on one chip. To reduce the area of the chip, the ink slot is a narrow and long rectangle, thus increasing the difficulty of the formation thereof.
Additionally, a nozzle plate is required on the conventional inkjet printhead. During assembly of the nozzle plate and the chip, precise alignment is required, thus increasing the assembly time. Also, assembly takes place individually, thus reducing the efficiency of the manufacture and increasing the cost.
Furthermore, since the ink chamber is open, in the conventional inkjet printhead, some liquid may flow back into the feed channel during dispensing. Thus, dispensing force may not be concentrated in the desired direction.
Moreover, the height of the ink chamber, the feed channel, and an adhesive layer between the chip and the nozzle plate are defined by organic polymer. Since the organic polymer is easily corroded by the ink, the ink may penetrate between the nozzle plate and the polymer, or between the chip and the polymer, thus reducing adhesive force and generating delamination.
FIG. 2 shows a conventional edge-shooting inkjet printhead 20. Numeral 21 represents a substrate, numeral 22 represents a heating area, numeral 23 represents a channel, numeral 24 represents a hole, numeral 25 represents a cover, and numeral 26 represents an orifice. During the formation of bubbles, driving force is not concentrated in the dispensing direction, reducing efficiency. Additionally, like the conventional inkjet printhead 10, the hole 24 is required in the cover 25, and the cover 25 must be precisely aligned with the substrate 21.
In U.S. Pat. No. 6,412,918, a back-shooting inkjet printhead is provided, requiring longer etching time, thus increasing cost and complicating process.